1. Field
The following description relates generally to wireless network communications, and more particularly to considerations for mitigating relay self-interference.
2. Background
Wireless communication systems are widely deployed to provide various types of communication content such as, for example, voice, data, and so on. Typical wireless communication systems may be multiple-access systems capable of supporting communication with multiple users by sharing available system resources (e.g., bandwidth, transmit power, etc.). Examples of such multiple-access systems may include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, orthogonal frequency division multiple access (OFDMA) systems, and the like. Additionally, the systems can conform to specifications such as third generation partnership project (3GPP) (e.g., 3GPP LTE (Long Term Evolution)/LTE-Advanced), ultra mobile broadband (UMB), evolution data optimized (EV-DO), etc.
Generally, wireless multiple-access communication systems may simultaneously support communication for multiple mobile devices. Each mobile device may communicate with one or more base stations via transmissions on forward and reverse links. The forward link (or downlink) refers to the communication link from base stations to mobile devices, and the reverse link (or uplink) refers to the communication link from mobile devices to base stations. Further, communications between mobile devices and base stations may be established via single-input single-output (SISO) systems, multiple-input single-output (MISO) systems, multiple-input multiple-output (MIMO) systems, and so forth.
In addition, relays can be used in some wireless communication systems to expand base station coverage, improve communication throughput, and/or the like. For example, relays can be assigned resources from a base station (much like a device), and can assign resources to a device (much like a base station). Upon receiving communications from the base station over the resources assigned by the base station, the relay can transmit the communications to one or more intended devices over resources assigned thereto by the relay, and vice versa. The relay can perform decoding/encoding of signals received before transmitting to the intended device or base station. Relays can operate in half duplex mode, where at any given time, the relays receive signals from a base station or transmit to a device, but typically not both.
Relays can also, however, operate in full duplex mode where the relay can transmit and receive at the same time (e.g., in the same frequency band). In this example, a relay can cause interference to itself, for example, by transmitting to a device on a frequency band at the same time as receiving signals from a base station on the same (or an adjacent or otherwise near) frequency band. Spatial separation of backhaul link antennas (e.g., for communicating with a base station) and access link antennas (e.g., for communicating with one or more devices) has been proposed to cure such interference, however, this solution is not always feasible for all relay deployments, and this solution can have high associated cost. Various interference cancellation techniques have also been proposed to cancel the interference after-the-fact.
Thus, improvements in the operation of relays are desired.